This invention relates to an oxygen blowing process for the production of steel. More particularly, the invention relates to a top oxygen blowing process for reducing carbon levels in the production of stainless steel.
It is known to produce stainless steel in a top blown oxygen converter wherein substantially pure oxygen is blown through a lance onto the surface of a chromium-containing iron bath maintained in a converter vessel. The oxygen introduced from the lance and onto the bath surface reacts with carbon, chromium, iron and oxidizes these as well as other elements in the molten iron charge in the converter. The thermodynamics of the system determines the oxygen compounds formed and the refining operation is controlled to promote the reaction of oxygen with carbon in preference to valuable alloying constituents such as chromium. To promote the reaction of oxygen with carbon, it is known to introduce oxygen below the surface of the charge through a tuyere in the bottom of the converter so that the bubbles of oxygen are distributed throughout the melt; and therefore oxygen is available to the carbon throughout the melt. It is also known that when refining with the converter at atmospheric pressure, it is helpful to introduce mixtures of oxygen and inert gas through a tuyere so that the bubbles will not become too concentrated with carbon oxides as these reactions proceed. It is also known that the oxygen is introduced through a lance in the top so that the oxygen impinges onto or beneath the surface of the bath, and an inert or endothermic gas is introduced through a tuyere in the bottom of the converter, while the interior of the vessel is at subatmospheric pressure as practiced in U.S. Pat. No. 3,854,932 which is incorporated herein by reference as if fully set forth herein.